초록
<P><B>Abstract</B></P> <P>A β-glucosidase gene from <I>Putranjiva roxburghii</I> (PRGH1) was heterologously expressed in <I>Saccharomyces cerevisiae</I> to enable growth on cellobiose. The recombinant enzyme was secreted to the culture medium, purified and biochemically characterized. The enzyme is a glycoprotein with a molecular weight of ∼68kDa and exhibited enzymatic activity with β‐linked aryl substrates like <I>p</I>NP-Fuc, <I>p</I>NP-Glc, <I>p</I>NP-Gal and <I>p</I>NP-Cel with catalytic efficiency in that order. Significant enzyme activity was observed for cellobiose, however the enzyme activity was decreased with increase in chain length of glycan substrates. Using cellobiose as substrate, the enzyme showed optimal activity at pH 5.0 and 65°C. The enzyme was thermostable up to 75°C for 60min. The enzyme showed significant resistance towards both glucose and ethanol induced inhibition. The recombinant <I>S. cerevisiae</I> strain showed advantages in cell growth, glucose and bio-ethanol production over the native strain with cellobiose as sole carbon source. In simultaneous saccharification and fermentation (SSF) experiments, the recombinant strain was used for bio-ethanol production from two different cellulosic biomass sources. At the end of the SSF, we obtained 9.47gL<SUP>−1</SUP> and 14.32gL<SUP>−1</SUP> of bio-ethanol by using carboxymethyl cellulose and pre-treated rice straw respectively. This is first report where a β-glucosidase gene from plant origin has been expressed in <I>S. cerevisiae</I> and used in SSF.</P> <P><B>Highlights</B></P> <P> <UL> <LI> β-glucosidase (<I>prgh1</I>) gene was cloned in frame with the <I>T. reesei xyn2</I> secretion signal and overexpressed. </LI> <LI> The <I>FUR1</I> gene of transformants was disrupted to generate autoselective strains. </LI> <LI> Physical properties make PRGH1 potentially an important industrial enzyme. </LI> <LI> Recombinant <I>S. cerevisiae</I> showed advantages in cell growth and ethanol production. </LI> <LI> First report where a plant β-glucosidase gene was expressed in <I>S. cerevisiae</I> and used in SSF. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>